CVE-2026-91768 Affecting php8.5 package, versions <8.5.9-0ubuntu2


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.56% (45th percentile)

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  • Snyk IDSNYK-UBUNTU2610-PHP85-21241208
  • published18 Oct 2026
  • disclosed25 Sept 2026

Introduced: 25 Sep 2026

NewCVE-2026-91768  (opens in a new tab)

How to fix?

Upgrade Ubuntu:26.10 php8.5 to version 8.5.9-0ubuntu2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream php8.5 package and not the php8.5 package as distributed by Ubuntu. See How to fix? for Ubuntu:26.10 relevant fixed versions and status.

The IPv6 branch of the FastCGI client access check compares only the first 12 bytes of a 16-byte IPv6 address, so listen.allowed_clients matches on a /96 prefix instead of the exact address. An attacker who can source an address sharing the first 96 bits with an allowed one passes the check and reaches the FastCGI endpoint.

CVSS Base Scores

version 3.1